1. Field
Some example embodiments relate to semiconductor devices and methods of manufacturing a semiconductor device using a metal oxide.
2. Description of the Related Art
An amorphous silicon layer has higher field effect mobility, can be applied to a high-speed operating circuit, and may be used to fabricate a complementary metal-oxide semiconductor (CMOS) circuit. Thus, the amorphous silicon layer has been widely used to form a semiconductor layer of a semiconductor device, such as a thin film transistor (hereinafter referred to as a ‘TFT’) or a diode.
Polycrystalline silicon may be formed through direct evaporation or may be formed by crystallizing an amorphous silicon layer into polycrystalline silicon. A method of forming polycrystalline silicon through direct evaporation is the most direct and a relatively easy method. However, when polycrystalline silicon is formed using this method, particles are generally smaller, have many defects and the quality of the polycrystalline silicon is not desirable, thereby deteriorating the performance of a polycrystalline silicon TFT.
Amorphous silicon may be crystallized according to a laser crystallization method, a thermal crystallization method, a complex crystallization method, or the like. In the laser crystallization method, amorphous or polycrystalline silicon is melted and recrystallized using a pulse laser or continuous laser. Thus, polycrystalline silicon having a few defects in particles may be formed. In the thermal crystallization method, a crystallization temperature is generally lowered using metal catalyst or complex energy. In a solid-phase crystallization method of forming low-temperature polycrystalline silicon by thermally treating amorphous silicon at a temperature around 600° C., the crystallization temperature is relatively high to cause a glass substrate to be bent and to change in size. Thus, the solid-phase crystallization method is difficult to apply to a manufacturing process.
Methods using metal catalyst may be divided into metal induced crystallization (MIC) and metal induced lateral crystallization (MILC). When a method of crystallizing polysilicon using a metal catalyst is used, a nickel (Ni) catalyst may remain in a polysilicon layer and a relatively large amount of leakage current may thus be generated during the manufacture of a silicon TFT.